Note: Descriptions are shown in the official language in which they were submitted.
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BREATH FRESHENING FILM
BACKGROUND OF THE INVENTION
Field of the Inventibn
This invention relates to a rapidly dissolvable orally consumable film for
delivering breath freshening and therapeutic agents to the oral cavity.
2. The Prior Art
Oral malodor is an undesirable condition that affects many people. Malodor of
the oral cavity, also known as halitosis or bad breath has been estimated to
afflict about
20-90 million people in the United States. To combat oral cavity malodor, the
art has
developed a variety of products including breath freshening gums, lozenges and
mints.
The use of these products is not always socially acceptable as they require a
sucking or
chewing action on the part of the consumer over an extended period of time
which can be
distracting in a social or business setting.
It is known to the prior art to use consumable films adapted to dissolve in
the oral
cavity containing flavoring agents for delivering breath freshening agents.
For example,
WO 00/18365 discloses a breath freshening film adapted to dissolve in a mouth
of a
consumer comprised of a water soluble polymer such as pullulon or
hydroxypropylinethyl cellulose and an essential oil selected from thymol,
methyl
salicylate, eucalyptol and menthol.
US 4,713,243 discloses a bioadhesive film for delivering therapeutic agents to
the
oral cavity which is capable of adhering to a wet mucosa surface, composed of
a water
soluble polymer matrix of 40-95% by weight of a hydroxypropyl cellulose having
a
molecular weight of about 100,000, 5-60% of a homopolymer of ethylene oxide
having a
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molecular weight from 3,000,000 to 5,000,000, 0-10% of a water-insoluble
polymer
selected from ethyl cellulose, propyl cellulose, polyethylene and
polypropylene, and 10%
of a plasticizer, the film having incorporated therein a pharmaceutically
effective amount
of medicament for the treatment of periodontal disease. The film is flexible
when wet so
as to be unobtrusive to the_user after it has been properly positioned and
placed in the
mouth.
US 5,354,551 discloses a water soluble film presegmented into dosage units,
the
film containing conventional toothpaste ingredients and formulated with
swellable
polymers such as gelatin and com starch as film forming agents which upon
application
to the oral cavity slowly disintegrate, thereby releasing an active agent
incorporated in the
film.
US 6,177,096 discloses a film composition containing therapeutic and/or breath
freshening agents for use in the oral cavity prepared from a water soluble
polymer such as
hydroxypropylinethyl cellulose, hydroxypropylcellulose and a polyalcohol such
as
glycerol, polyethylene glycol. When applied to the oral cavity, the film
exhibits instant
wettability followed by rapid dissolution.
Despite the existence in the prior art of rapidly dissolvable orally
consumable
films, there is still room for improvement in such films, namely the speed
with which the
film dissolves in the mouth. Unless the film is substantially instantly
dissolvable when
placed in the mouth, that is within about 30-40 seconds, the undissolved film
residue
imparts an unacceptable, unpalatable, slimy feel to the palate of the
consumer.
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SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a rapidly
dissolvable,
orally consumable film composition for delivering breath freshening agents to
the oral
cavity, the composition being comprised of a homogeneous mixture of a water
soluble,
low viscosity hydroxyalkylinethyl cellulose, a water dispersible starch and a
flavoring
agent.
The hydroxyalkymethyl cellulose serves as a strong film former to give the
film
the necessary mechanical strength and maintain the integrity of the film at
elevated
temperature. The starch ingredient increases the stiffness of the film and
reduces the
curling of the Olin. The presence in the film of the starch ingredient is also
critical to the
practice of the present invention for in the absence of the starch, the film
tends to curl up
after manufacture which is undesirable in the packaging and ultimate use of
the film.
Upon administration of the film of the present invention, due to its rapid
dissolution, there is provided a burst of breath freshening agent to the oral
cavity, without
any lingering unpleasant residue on the users palate.
DETAILED DESCRIPTION OF THE INVENTION
The film of the present invention comprises hydroxyalkylinethylcellulose as a
film forming agent combined with starch, and a flavoring agent particularly an
essential
oil as the breath freshening agent. The film can further comprise water,
additional film
forming agents, plasticizing agents, flavoring agents, antimalodor agents,
surfactants,
emulsifying agents, coloring agents, sweeteners and fragrances.
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In preparing the film according to the present invention, a low viscosity
hydroxyalkylmethyl cellulose; a starch ingredient, a breath freshening agent
and other
film forming ingredients are dissolved in a compatible solvent to form a film
forming
composition. The hydroxyallcyl cellulose to starch ratio (by weight) may vary
from about
i :3 to about 4: l and preferably about 1:1.5 to about 2.5:1.
The composition is cast on a releasable carrier and dried. The carrier
material
must have a surface tension which allows the film solution to spread evenly
across the
intended carrier width without soaking to form a destructive bond between the
film and
carrier substrates. Examples of suitable carrier materials include glass,
stainless steel,
Teflonand polyethylene-impregnated paper. Drying of the film may be carried
out at
high temperature using a drying oven, drying terminal, vacuum drier, or any
other
suitable drying equipment which does not adversely effect the ingredients of
which the
film is composed.
The film once formed is segmented into dosage units by die-cutting or slitting-
and-die-cutting. The segmented film has a strip width and length corresponding
to about
the size of a postage stamp, generally about 12 to about 30 millimeter in
width and
about 20 to about 50 millimeters in length. The film has a thickness ranging
from about
15 to about 80 micrometers, and preferably about 30 to 60 micrometers.
The film is shaped and sized to be placed in the oral cavity. The film is
flexible
and adheres to a surface in the mouth, usually the roof of the mouth or the
tongue, and
quickly dissolves, generally in less than 30-40 seconds.
The film forn~ing agent used in the films according to the present invention
is
preferably a low viscosity hydropropylmethyl cellulose polymer (HI'MC). It is
critical to
the present invention that the HPMC have a viscosity in the range of about 1
to about 40
millipascal seconds (mPa~s) as determined as a 2% by weight aqueous solution
of the
HPMC at 20 °C using a Ubbelohde tube viscometer. Preferably the
HPMC has a
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viscosity of about 3 to about 20 mPa~s at 20°C . As will hereinafter be
demonstrated, it is
critical to the practice of the present invention that a low viscosity
hydroxyalkylmethyl
cellulose be used in the preparation of the film matl~x. At viscosities
appreciably higher
than about 40 mPa~s, for a given film thickness, the lower the viscosity of a
hydroxyalkyl
methyl cellulose such as HPMC, the more rapid the dissolution of the film
matrix and the
burst of breath freshening ingredients.
The hydroxyalkyl methyl cellulose is incorporated in the film composition in
amounts ranging from about 10 to about 60% by weight and preferably about 15
to
about 40% by weight.
The HPMC polymer is a preferred hydro~.yalkylmethyl cellulose polymer and is
available commercially from the Dow Chemical Company under the trade
designation
Methocel ES Premium LV. Methocel E5 Premium LV is a USP grade, low viscosity
HPMC having 29.1% methoxyl groups and 9% hydroxyproxyl group substitution. It
is a
white or off=white free-flowing dry powder. As a 2 wt% solution in water as
measured
with a Ubbelohde tube viscometer it has a viscosity of 5.1 mPa~s at
20°C.
Cold water swellable, physically modified and pregelatiniaed starches are
particularly useful as texture modifier to increase the stiffness of the
hydroxyalkyl methyl
cellulose polymer films of the present invention, as the breath film prepared
by HPMC
alone, at the thicknesses described for the present invention, tends to curl
up after it is
cast and dried . To prepare such starch products, the ~anular starch is cooked
in the
presence of water and possibly an organic solvent at a temperature not higher
than 10°C
higher than the gelatinization temperature. The obtained starch is then dried.
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Pregelatinized corn starch is available commercially. A preferred starch is
available under the trade designation Gerestai Polar Tex-Instant 12640 from
the Cerestar
Company. This Cerestai starch is a pregelaterized, stabilized and crosslinked
waxy
maize starch. It is readily .dispersible and swellable in cold water. In its
dry form, it is a
white free flowing powder with an average particle size no greater than 180
micrometers
and 85% of the particles are smaller than 75 micrometers. It has a bulk
density of
44Ibs/ft3.
The Cerestar starch has excellent cold storage and freeze-thaw stability. It
has a
rapid hydration rate and can reach extremely high viscosity without cooking.
It has a -
smooth and creamy texture similar to cook-up starches. It also has excellent
paste clarity
and a bland flavor.
1 S The pregelatinized starch is present in the film of the present invention
in an
amount ranging from about 5 to about 50% by weight and preferably about 10 to
about
35% by weight.
Flavor agents that can be used to prepare the breath freshening filin of the
present
invention include those known to the spilled artisan, such as natural and
artificial flavors.
These flavorings may be chosen from synthetic flavor oils and flavoring
aromatics,
and/or oils, oleo resins and extracts derived from plants, leaves, flowers,
fruits and so
forth, and combinations thereof. Representative flavor oils include: spearmint
oil,
cinnamon oil, peppermint oil, clove oil, bay oil, thyme oil, cedar leaf oil,
,,oil of nutmeg,
oil of sage, and oil of bitter almonds. These~flavor agents can be used
individually or in
admixture. Commonly used flavors include mints such as peppermint, artificial
vanilla,
cinnamon derivatives, and various fiuit flavors, whether employed individually
or in
admixture. Generally, any flavoring or food additive, such as those described
in
Chemicals Used in Food Processing, publication 1274 by the National Academy of
Sciences, pages 63-258, may be used. The amount of flavoring agent employed is
normally a matter ofpreference subject to such factors as flavor type,
individual flavor,
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and strength desired. Generally the flavoring is incorporated in the film of
the present
invention in an amount ranging from about 2.0 to about 10% by weight and
preferably
about 5 to about 8% by weight.
Sweeteners useful in the practice of the present invention include both
natural and
artificial sweeteners. Suitable sweetener include water soluble sweetening
agents such
as monosaccharides, disaccharides and plysaccharides such as aylose, ribose,
glucose
(dextrose), mannose, glatose, fructose (levulose), sucrose (sugar), maltose,
water soluble
artificial sweeteners such as the soluble saccharin salts, i.e., sodium or
calcium saccharin
salts, cyclamate salts dipeptide based sweeteners, such a L-aspartic acid
derived
sweeteners, such as L-aspartyl-L-phenylalaine methyl ester (aspartame).
In general, the effective amount of sweetener is utilized to provide the level
of
sweetness desired for a particular composition, will vary with the sweetener
selected.
I5 This amount will normally be about 0.01 % to about 2% by weight of the
composition.
The compositions of the present invention can also contain coloring agents or
colorants. The coloring agents are used in amounts effective to produce the
desired color
and include natural food colors and dyes suitable for food, tjrug and cosmetic
applications. These colorants are known as FD&C dyes and lakes. The materials
acceptable for the foregoing spectrum of use are preferably water-soluble, and
include
FD&C Blue No.2, which is the disodium salt of 5,5-indigotindisulfonzc acid.
Similarly,
the dye la~own as Green No.3 comprises a 15 triphenylmethane dye and is the
monosodium salt of 4-[4-N-ethyl-p-sulfobenzylarnino) diphenyl-methylene ]- [ 1-
N-ethy
1- N-sulfonium benzyl)- 2,5-cyclo-hexadienimine ] .A full recitation of all
FD&C and
D&C dyes and their corresponding chemical structures may be found in the Kirk-
Othrner
Encyclopedia of Chemical Technology, Volume 5, Pages 857-584.
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Active breath freshening agents can be incorporated into the film composition
of
the present invention to form the breath freshening strips of the present
invention. The
active ingredients include zinc gluconate, zinc citrate and/or alpha ionone.
These agents
function in maslsing mouth odor and reducing volatile odor causing bacterial
sulfur
compounds. These agents may be incorporated in the film composition of the
present
invention at a concentration of about 0.1 to about 2.0% by weight and
preferably about
0.15 to about 0.5% by weight.
The present invention is illustrated by the following examples.
Example 1
A breath freshening film was prepared by using the ingredients listed in Table
I
below. In preparing the film, the HIVIPC polymer l~~Iethocel ESLV having a
viscosity of
5.1 mPa~s (2% aqueous solution) was added to deionized water at 23°C,
zinc gluconate
trihydrate was added and the solution stirred for 5 minutes. To this solution
was added
the pregelatized starch Cerestai Polar Tex Instant 12640 and stirred
vigorously for about
one hour until the starch was completely dispersed and a homogeneous mixture
was
formed. To this mixture was added the dye, FD&C green #3, and mixed for 10
minutes
after which the emulsifier polysorbate 80 was added and mixed for an
additional 15
minutes. Thereafter spearmint flavor, was thoroughly mixed for an additional
40 minutes
to form a slurry emulsion. The weight ratio of HPMC to pregelatinized starch
was 1.2.
The emulsion was then cast on a polyethylene coated paper at 25°C and
dried at 110°C to
form a solid thin film.
To determine the speed of dissolution of the film in water, the film was
floated on
a clean and smooth water surface at °C. The thin film (40 um thick,
1.25" x 0.875")
disintegrated completely in 30 seconds after being placed afloat on a clean
and smooth
water surface.
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The film was evaluated for a breath freshening benefit by in-vitro volatile
sulfur
compound (VSC) reduction assay. In this assay a known amount of breath film is
dissolved in a 3.0 milliliters (ml) of saliva in a glass vial. After
incubation at 37°C
overnight, the headspace of the solution is sampled and analyzed for the VSC.
The VSC
assay results are presented in Table II.
TABLE I
Ingredients Wt.
Water ' 76.71
HPMC 9.075
Corn Starch (pregelatized) 7.563
Flavor 5.85
Polysorbate 80 0.35
Zinc gluconate 0.21
Sucralose 0.24
FD&C green 0.002
TABLE II
VSC ASSAY OF THE BREATH FILM
~~ Sample No. Film Quantity in Saliva (mg/3mL) VSC Reduction (%)
1 0 0
2 10 5
3 20 11
4 30 17
The VSC results recorded in Table II demonstrate that the breath freshening
benefit of the film is proportional to the amount of film exposure.
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Ea:am Ip a II
Three different breath films were prepared following the procedure of Example
1
according to the general formula of Table III. The three films shared the same
formula
except for the type of Methocel HPMC polymer used. Film A was prepared using
Methacel*ESLV having a viscosity of 5.1 mPa-s. For purposes of comparison,
Filins B
and C were prepared using HPMC polymers lVlethocel*F50 and Methocel~E4M having
a
viscosities of 50 and 4000 mPa~s respectively. The dispersion rates of the
three different
films were tested using the same surface-floating procedure as used in Example
I and the
results are listed in Table IV.
TABLE III
GENERAL FORMULA OF FILNIS A, B AND C
Ingredients Weight
Methocel ~' 6.85
Geresta~'Polar Tex Instant 5.70
12640
Tween 80 0.50
Propylene glycol 4.00
Sucralose 0.125
Zinc gluconate O.I73
FD&G Green #3 0.002
Spearmint flavor 6.0
Cooling agent 0.50
Deoinized water 76.05
TABLE IV
DISPERSION RATES OF FILM A, B AND C
Film Base
Film
Formula MethocelIiPMC Starch Methocel/Film Dispersion
Viscosity Starch Thicknessrate
ratio
(mPasl by wt. (micrometers)(seconds)
~
A ES 5.1 Cerestar*1. 42 40
2
~ B F50 50 Cerestar1.2 42 72
*
C E,4M 4000 Cerestar1.2 39 205
*
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The results recorded in Table IV indicate that films prepared using
viscosities of
50 mPa~s or more dissolve appreciably slower than a film prepared using a HPMC
having
a viscosity less than 50 mPa~s.
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